FUEL CELL ASSEMBLY HAVING FEED-BACK SENSOR

• US 20110151345A1
• Filed: 08/20/2008
• Published: 06/23/2011
• Est. Priority Date: 08/20/2007
• Status: Active Grant

• Current Assignee: Fuel Cell Technology Sweden AB
• Original Assignee: MyFC AB (myFC Holding AB)
• Inventors: Jonsson, Eric, Lundblad, Anders, Ekstrom, Henrik
• Granted Patent: US 8,889,307 B2
• Time in Patent Office: Days
• US Class Current: 429/429
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2250/30 Fuel cells in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04223 during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04798 of fuel cell reactants
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/1097 Fuel cells applied on a support, e.g. miniature fuel cells deposited on silica supports
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: Y02B 90/10 Applications of fuel cells in buildings
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A sensor cell (1010) for control purposes usable in an assembly (1000) of fuel cells of the type having a membrane electrode assembly (MEA) interposed between an anode gas diffusion layer and a cathode gas diffusion layer, and first and second current collectors coupled to the anode and cathode gas diffusion layers (GDL), respectively. The sensor cell (1010) is preferably coupled so that it shares the negative current collector (1050) with last fuel cell in the in-plane fuel cell assembly (1000), and is short-circuited by a resistor (1070) to provide a voltage signal, indicative of the status of the assembly in operation.

Claims

1. A fuel cell assembly, comprising

at least one power generating fuel cell and a sensor fuel cell;

wherein

said sensor cell has the same general constitution as the other cell(s) in the assembly, i.e. comprising an anode GDL, a cathode GDL, a MEA interposed between said GDLs, and which is located at the hydrogen gas outlet from the other cell(s) so as to receive its fuel from residual fuel in the gas outlet from the other cells, wherein the anode and the cathode of the sensor cell are connected with each other via a resistor (R).

2. A fuel cell assembly as claimed in claim 1, wherein the sensor cell is coupled so that it shares the negative current collector with the last fuel cell in the in-plane fuel cell assembly

3. A fuel cell assembly as claimed in claim 1, wherein the cells in the assembly are arranged in an in-plane configuration.

4. A fuel cell assembly as claimed in claim 1, wherein said sensor cell is smaller than the operative cell(s) in the assembly.

5. A fuel cell assembly as claimed in claim 1, comprising a source of pressurized gas, and a dead end valve at the gas outlet of the fuel cell device, wherein said sensor cell is placed after the fuel cells in the gas flow direction but before the dead end valve.

6. A fuel cell assembly as claimed in claim 5, wherein the dead-end valve has a small leakage, so as to avoid accumulation of non-fuel gases.

7. A fuel cell assembly as claimed in claim 6, wherein the sensor cell is capable of indicating when the power draw is larger than what a max-flow limit of the hydrogen source can support.

8. A fuel cell assembly as claimed in claim 5, wherein the dead-end valve with a small leakage has a pressure dependent functionality so that it opens at a threshold value, preferably at 1-7 psi (6.9 kPa-48.3 kPa).

14. An electrical device comprising a fuel cell assembly as claimed in claim 1.

15. Electrical device as claimed in claim 14, further comprising a control unit which is adapted to regulate the supply of hydrogen to the assembly or the power draw from the assembly in response to the voltage of the sensor cell.

16. An electrical device as claimed in claim 14, which is a power source for an electronic apparatus.

17. An apparatus comprising a unit operating by electric power, and a chargeable battery, comprising means for connecting a device as claimed in claim 15.

18. An apparatus as claimed in claim 17, comprising a plurality of fuel cell units, suitably each unit comprising 3-8 cells, connected in parallel with respect to gas flow and electrical current, each unit having one sensor cell, and optionally further comprising a DC/DC-converter connected to each fuel cell unit and power control electronics.

19. An apparatus as claimed in claim 18, wherein the signal from each sensor cell is used by each power control unit to control the output power so that all hydrogen gas is consumed, irrespective if the flow is different in the different fuel cell units.

20. Method of operating a fuel cell assembly as claimed in claim 1, said method comprising the steps of:

supplying hydrogen gas to the fuel cell(s);

monitoring the voltage of the sensor cell;

during operation, continuously monitoring the voltage of the sensor cell;

when the voltage of the sensor cell deviates from a predefined value, performing a control function to adjust the performance of the assembly.

21. Method as claimed in claim 20, further comprising the steps of:

at start-up, consecutively and individually short-circuiting the cells in the assembly for a predetermined time;

between each short-circuiting, testing the sensor cell;

when all cells have been short-circuited, providing continuous supply of fuel.

22. Method as claimed in claim 20, wherein the control function comprises adjusting the fuel feed.

23. Method as claimed in claim 20, wherein the control function comprises adjusting the power draw from the fuel cell assembly.

24. Method as claimed in claim 20, further comprising

if the sensor voltage drops during operation, performing the step of

a) decrease the power draw from the cell assembly;

and if the voltage does not increase enough

b) momentarily stop the power draw.

9. A sensor fuel cell, having the same constitution as an operational/operative power fuel cell, and comprising

a resistor (R) coupled across the anode/cathode,

a fuel inlet connectable to an outlet from an operative fuel cell, and terminals connectable to a control unit for providing a voltage signal to said control unit, said voltage usable for controlling the operation of a fuel cell assembly, to which said sensor cell is connectable.

10. Sensor fuel cell as claimed in claim 9, adapted to consume 1-5% of the gas feed to the fuel cell assembly.

11. Sensor fuel cell as claimed in claim 9, wherein the resistor is dimensioned as follows for a sensor cell having a working voltage of U_work:

R=U_work/I_reg.

wherein

I_reg=E_gas×

I_nom×

N

E_gas is the excess gas supplied to the sensor cell, I_reg is the current through the sensor cell for an assembly of N cells having a nominal current of I_nom.

12. Sensor fuel cell as claimed in claim 9, wherein the resistor has a resistance of 0.5-2 Ohms, preferably 0.75-1.25 Ohms.

13. Sensor fuel cell as claimed in claim 9, which is smaller than the operative cell(s).